I've been wanting to do this for a few years and I've finally pulled the trigger and ordered plans and a few parts for a 22-string Shepard harp from Harpkit. I'm going to source my own wood with exception of the soundboard which I ordered from Harpkit as Finnish Aircraft Birch 3mm ply. I've ordered enough hardware for two harps. I'm going to build the first according to the plans. I've looked for a harp making forum but haven't found anything. The parts and plans should arrive next week. I'm eager.

I made a 26 string harp from the Musicmaker's Limerick harp plans a while back (geez, it's more that 12 years ago now). I did use thin ply for the soundboard, but don't recall where I got it. IIRC I added the sharping levers later, I would recommend adding them when you build it.

I started a bigger one using the Robinson plans but that project got shelved for a while.

I'll be sure to check out the library. Purchasing sharping levers will proceed once the project has proven to be successful -- they're sort of expensive.All things seem to point to the sound board as being the heart of tonal performance. Deciding on the soundboard construction has been the biggest reason I've delayed the project. Although all sources seem to talk about the soundboard, there are only one or two that specifically address the construction with any type of specification and even then its lacking. It comes down to a magic compromise of having the soundboard thin enough and tapered properly to be lively versus being strong enough to deal with the tension of all of the strings so it doesn't self destruct. The first harp I build will be built exactly to the blueprints provided so at least there is a likelihood of success. A solution has occurred to me concerning the stress of string tension and I'd like some feedback. Why not incorporate a structural member an inch or two under the soundboard and anchor the strings to it instead of the sound board -- acting like a tailpiece on an archtop guitar. Offset the anchor point somewhere around 30 to 40 degrees from where the string travels through the soundboard so there is a break angle at the soundboard's/string hole. Consider a one inch wide anchoring spar centered directly under the string holes of the soundboard with holes that enable the strings to be tied to the anchoring spar alternating left-right-right... with the resulting angles being offset both lateral and longitudinal from the soundboard holes -- northeast-northwest-northeast... The full tension of the string is no longer applied to the soundboard. Thoughts...

I have built a few small harps and repaired a few for people. If you want to build a solid spruce soundboard you can buy a few "A" grade guitar tops and edge glue them to create the length of the soundboard. The grain of a harp soundboard runs side to side rather than top to bottom. On better harps it gets thinner as the soundboard narrows toward the treble strings. Hardwood reinforcing strips are inside and outside of the soundboard that the strings pass through and sometimes there are metal "shoes" or string guides to keep the strings from cutting into the soundboard. I've used pop rivet "heads" without the "mandrel " part for string shoes. Some harps don't have sharping levers and some have them on the F's and C's which allows a quick change from the key of C to the keys of G and D. The sharping levers need to be mounted a semitone below the length of the open string (plus a little adjustment either way) so as the strings get longer the neck gets wider. As to the spar idea I'm wondering if it would behave a bit more like a lyre than a harp. Don't know.

Finished the first of three using the plans. I generally stayed to the plans I purchased but applied a change or two to make it a little more structurally hardy. The build is much more like making a piece of furniture than a musical instrument but I cannot fault the tone. It makes a wonderful tone that actually sounds like a harp. I used African mahogany for the pillar, the neck and structure of the sound box. The soundboard and back are 3mm aircraft grade birch from Finland as suggested by the plans. The trim on the soundbox and the center reinforcement is some jatoba that I had already. My only major change was the use of maple on the left side and how it reinforced the neck. Its what I had on hand and is overkill for strength. I'm not sure whether I like the contrast or hate it but it didn't really add any significant weight and I know that the neck isn't going to split. It was an impulse modification but the mahogany I had ended up to be about 3/16" thinner than the spec after surface planing and felt very light. I'm pleased with the result and will build more harps

I would really like to make contact with other harp makers to share ideas and learn more. I checked out Jims youtube vids -- like what I saw. His server is down on the link associated so I'm unable to contact him. Its been a week or two since I strung up my Shepard harp to pitch and its getting more tuning stable every day. The strings supplied by the vendor are probably not the highest quality and I'd like to see what the result would be with really good quality classical strings such as ProArts or others that I use on my classical guitars. The plans are good but I feel the plans are aimed at non-luthiers. There are one or two critical procedures that need to be overcome but the rest of the build is really simple and its comparatively inexpensive to make these compared to making a guitar. I have two more harps in progress using the basic geometry/ideas of the Shepard harp plans. I'm also trying wood carving for the first time. This is on African mahogany. I'm eager to learn about making my own soundboards. I think my email address is available and I would be grateful to connect with other harp makers.

The latest. This is #2 using the same plans again. This time, all mahogany construction except for the sound board itself which is the imported birch aircraft ply. I added a little more structural strength for steel strings. With the steel strings , the tone was terrible so I stayed up until 2AM removing them and installing a nylon string set -- nice result.

Steel strings sound terrible on harps, as you've observed. There seem to be several reasons. To see why you need to think about how strings work, and how harps work differently from guitars.

When you pluck a string it actually produces three different periodic forces signals on the end point at the soundboard. If you think of the string as vibrating 'up and down' it's pulling that point up and down along with it. It can also, of course, move from side to side, and that component of the motion doesn't produce sound from this signal. This 'transverse' signal is, in general, the strongest one the string produces.

As the string vibrates it gets longer and shorter, and that makes the tension change. Because the string gets longer twice for every full cycle of vibration, this signal is 'frequency doubled'; it has energy at even multiples of the string's fundamental pitch. This signal has much less force than the 'transverse', usually about 1/7 of the amplitude.

The third signal is the 'longitudinal' wave, a compression wave that's produced in a string any time you pluck it off center in it's length. The frequency of this is almost solely a product of the string material and length, and bears no necessary relationship to the pitch of the string. It' usually somewhere around the 7th or 8th partial of the string. In pianos they call this the 'clang tone'; on guitars it's the 'zip tone' that you hear when you run a finger along a wound string. It's a little hard to compare the strength of this signal with the other two, for one thing, it tends to come and go periodically depending on a bunch of factors. It does seem to be pretty large in amplitude in some cases.

Guitars are almost solely driven by the 'transverse' signal. It's pulling the bridge 'up and down', which moves the top like a loudspeaker cone. It's fairly easy to do, and effective at making sound. Both the 'tension' and 'longitudinal' signals work by rocking the bridge fore and aft. This is hard to do; guitars are designed to resist this. It's also less efficient, since part of the soundboard moves 'up' as another part moves 'down'. Guitars thus get some energy from the 'tension' and 'longitudinal' signals, but not enough to add any real power; it mostly produces changes in the timbre, particularly depending on the height of the strings off the top.

Harps are another matter. Because the strings pull upward on the soundboard all of the string signals, the 'transverse' , 'tension' and 'longitudinal', produce sound about equally effectively depending on how much force they put in. The proportional effectiveness depends to some degree on the exact string angle. As a string material, steel tends to have relatively more energy in the 'tension' signal as compared with the 'transverse'. This will not be a problem on a harp, and my actually produce a nicer sound. The 'longitudinal' signal seems to be the main culprit.

The problem here is two fold; the 'longitudinal' signal is stronger on steel strings for the same reasons the 'tension' signal is: the difficulty of stretching a steel string. More than that, though, is the fact that it's at a higher frequency on steel than nylon. This in itself tends to make it more audible and irritating: your hearing tends to be more sensitive at those high frequencies, and pitches up in the upper octave of the range (say, above 15kHz) are particularly bad. You'd be in that range of frequencies with the 'clang' tone of your middle octave with steel strings. The fact that the frequency is generally dissonant only adds insult to injury.

Metal strung harps use brass or bronze wire in general. The 'clang tone' is lower in pitch due to the properties of the material, and not as powerful. These strings generally tune about a fourth or fifth lower in pitch than nylon or steel, so even though the clang tone pitch is still dissonant, at least it's not in such an irritating range.

You may have noticed that I said that the 'clang tone' is driven when you pluck (or strike) the string off center in it's length. Harpists are often told to play in the middle of the string, and that will cut the 'clang tone' down to nothing, or nearly so. Playing a guitar string in the middle sounds lousy: it lacks all of the even partials because you've plucked it just where the string wants to be still for those tones. They're there in the 'tension' signal, but not very effective at producing sound. With the strings pulling upward on the soundboard on a harp the 'tension' signal can get into the act in a useful way. Plucking the string in the middle actually maximizes the power of the tension signal relative to the transverse, and can produce a full tone with all the partials on a harp.

All of which is the long way around to saying: "There are reasons behind tradition".

As far as using 'better' strings; so far as I know all of the string manufacturers get their material from the same big companies, like DuPont or BASF. There are dozens of kinds of 'nylon' with different properties, and the string makers pick the one that will make the sound they want. There can be problems with the stock they get from the manufacturers: often the nylon in the middle of a spool will be squashed out of round, which makes it vibrate in an odd way (to put in mildly!). Some of the guitar string makers try to correct this by grinding the strings round, and sometimes it works. It's not a different material, though. Harp string suppliers sell the same stuff, and they buy some of it colored blue and red. That's hard to do with plain clear nylon.

Alan, Sincere gratitude for the time you took in your explanation. A mentor of mine told me once that there are three kinds of information in luthery, Myths, Legends, and Facts. I strive to learn and apply the facts and the science as much as I can although I often apply the science by the seat of my pants. When I have a good result and don't know why it's mojo. I've read your post twice and will read it a few more times so it can sink in.